Quinpirole hydrochloride

The cDNAs encoding various human G protein subunits and receptors were obtained from UMR cDNA Resource Center (Rolla, MO, USA). Molecular biology reagents, anti-Flag and Fluo-4 AM were purchased from Invitrogen (Carlsbad, CA, USA). Human embryonic kidney HEK293 cells (CRL-1573) were obtained from American Type Culture Collection (Rockville, MD, USA). Cell culture reagents were obtained from Thermofisher Scientific (Waltham, MA, USA). Polyethylenimine (PEI) (Linear, MW 25,000) was purchased from Polysciences, Inc. (Warrington, PA, USA). Pertussis toxin (PTX) was ordered from List Biological Laboratories (Campbell, CA, USA). Forskolin and quinpirole hydrochloride were purchased from Tocris Bioscience (Bristol, UK). The [³H]adenine was purchased from American Radiolabeled Chemicals (St. Louis, MO, USA) and PerkinElmer (Waltham, MA, USA), while the scintillation fluid (Optiphase Hisafe 3) and [³H]inositol were purchased from PerkinElmer (Waltham, MA, USA). Anti-Gα_i1 primary antibody was from Aviva Systems Biology (San Diego, CA, USA). Anti-Gα_i2 and anti-Gα_i3 antibodies were from Santa Cruz Biotechnology (Santa Cruz, CA, USA). Anti-HA and anti-β-actin were from Roche Molecular Biochemicals (Indianapolis, IN, USA). EZview™ Red anti-Flag® M2 Affinity Gel and other chemicals were purchased from Sigma (St. Louis, MO, USA).

(−)-Quinpirole hydrochloride (Tocris, Bristol, UK) was dissolved in 0.9% saline and was administered intraperitoneally once daily (one hour before restraint) at doses of 5 mg/kg/day during chronic stress. Control group received an equivalent volume of 0.9% saline.

Quinpirole hydrochloride, eticlopride hydrochloride, and gabazine (SR 95531 hydrobromide) were purchased from Tocris Bioscience. (-)-Nicotine hydrogen tartrate salt was purchased from Sigma-Aldrich. 15 min after the first nicotine injection, quinpirole 1 mg/kg was administered intravenously. 5 minutes later, eticlopride 1 mg/kg was administered intravenously. When the neuron activity was returned to baseline, a second nicotine injection was performed. Once D2-R pharmacology was applied, no further neurons were recorded and the animal was discarded.